The conventionally-known power-supply device of the AC-DC converter generally comprises a PFC (power factor correction) converter composed of a rectifier using a diode bridge, and a boost converter.
In addition, US 2009-0303762A1 discloses a technology of the power-supply device using two buck converters, comprising the first buck converter and the second buck converter each composed of a diode, a switch, an inductor and an output capacitor, wherein the first buck converter is operated during a positive half-cycle period of an AC input voltage, and the second buck converter is operated during a negative half-cycle period of the AC input voltage, and obtaining a sum voltage of both ends voltage of each of the output capacitor as a DC output voltage.